This invention relates to local number portability in telecommunication systems and, more particularly, to a local number portability architecture that supports service provider portability, location portability and service portability.
Presently, a telephone subscriber""s directory number is usually a geographic North American Numbering Plan (NANP) number having the NPA-NXX-XXXX format. In this format, NPA is the number plan area, or area code, NXX is the central office code and XXXX identifies the station number. This geographic number (GN) identifies the subscriber as well as the physical location of the subscriber""s terminal. The geographical information is derived from the NPA+NXX, which uniquely identifies the subscriber""s central office. When a telephone user subscribes to telephone services from a particular central office, he or she is assigned a station number with the NPA+NXX of that central office. As a result, it is not possible for telephone users to retain their directory number when they are served by another central office, such as is the case when they move or change service providers.
At present, telephone subscribers have many choices of long distance carriers. Each long distance carrier sets its own rates and separately bills the subscriber. However, telephone subscribers presently have no choice with respect to local telephone service. For example, in the New England area, all local service is provided by NYNEX. In order to introduce competition into the local service market so that a subscriber may select from several local service providers, alternative service providers may own and/or operate switching offices within a local area. However, the present numbering plan described above is not compatible with multiple service providers in a local area. If a subscriber changed service providers, it would be necessary to change directory numbers. To overcome these difficulties, the concept of local number portability has been introduced.
Local number portability (LNP) is a telecommunication service that offers subscribers service provider portability, location portability and service portability. Service provider portability gives subscribers the ability to obtain local telephone service from any service provider that offers services in the subscriber""s area, while retaining the same telephone number. Location portability permits subscribers to retain their telephone number when they relocate to a new location outside the serving area of their serving central office. Today, subscribers can retain their telephone number only when they relocate within the serving area of their current serving central office. Service portability allows subscribers to obtain any available telecommunication services, regardless of the capabilities of their current serving central office, while retaining their telephone number. Currently, the service features available to subscribers are determined by the capabilities of their current service central office.
A technique known as xe2x80x9cforeign exchangexe2x80x9d has been used by local telephone companies to support location portability beyond the coverage area of the serving office. This technique allows a telephone subscriber to keep his or her telephone number when he or she moves to a new location within a given distance from the old location. The subscriber pays a monthly fee for this service. Part of the monthly fee is tariffed based on the distance between the old serving end office and the new serving end office. The foreign exchange service physically connects the telephone user""s phone at the new location to the previous serving end office. Therefore, the telephone user is actually served by the. previous serving end office. The line that connects the telephone user""s phone to the previous serving end office typically consists of a trunk circuit between the previous serving end office and the local end office that serves the foreign exchange service subscriber. As a result, significant network resources are required to serve a single subscriber.
The foreign exchange service is typically very expensive. In addition, people living in the same area as the foreign exchange subscriber, such as a next door neighbor, are required to pay toll charges when they call the foreign exchange subscriber. To avoid this situation, the foreign exchange subscriber may need to have another phone line with a local telephone number. This means a second telephone number and another monthly fee.
The foreign exchange service has a distance limitation. It cannot be offered if the serving end office and the telephone user are located in different LATA""s. Even though the foreign exchange service expands the scope of location portability from within the coverage area of the serving end office to within a LATA, it is not a robust location portability service. The telephone company needs to provide additional facilities to support foreign exchange service, because the telephone user""s phone is physically connected to the previous serving end office. The foreign exchange technique inefficiently uses network resources. Furthermore, service provider portability is not supported by this technique.
According to the present invention, methods and apparatus for telecommunication call processing with local number portability are provided. The method for call processing comprises providing a local number portability switch and a local number portability database accessible by the local number portability switch. The local number portability database contains a table for translating geographic numbers to routing information. The local number portability switch queries the local number portability database using a dialed geographic number in response to initiation of a call. The local number portability database translates the dialed geographic number to corresponding routing information and returns the corresponding routing information to the local number portability switch, and the local number portability switch uses the corresponding routing information to route the call.
The local number portability database may comprise a global local number portability database for translating the dialed geographic number to a routing number. The global local number portability database can be a single physically large database containing all subscriber information; the subscriber information can be copied into several physical databases; or the subscriber information can be partitioned into several physical databases. In another configuration, the local number portability database may comprise a global database for translating the dialed geographic number to intermediate routing information, such as a service provider identification, a carrier identification code and/or a trunk group identification, or an intermediate switch address. The intermediate routing information may be used to query a service provider database, which translates the dialed geographic number to a routing number, or used to route the call to an intermediate switch. which can query a service provider database. Each service provider database contains routing numbers for its own subscribers. In another configuration, each service provider database contains combined routing information, including routing numbers for its own subscribers and intermediate routing information for subscribers of other service providers.
In one embodiment, the routing number identifies a destination switch corresponding to the dialed geographic number. In another embodiment, the routing number uniquely identifies the destination switch and the subscriber corresponding to the dialed geographic number.
According to another aspect of the invention, apparatus for telecommunication call processing comprises a local number portability switch and a local number portability database accessible by the local number portability switch. The local number portability switch can be an originating switch, an intermediate switch or a destination switch that has query capability. The local number portability database can be a global database, a service provider database or a combined service provider database. The local number portability switch includes means responsive to initiation of a call for querying the local number portability database using a dialed geographic number. The local number portability database includes means for translating the dialed geographic number to corresponding routing information and means for returning the corresponding routing information to the local number portability switch. The local number portability switch includes means responsive to the corresponding routing information for routing the call.